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FS: Pair of RCA BA-31A Germanium Preamplifiers

Posted: Wed Nov 29, 2006 1:54 pm
by sandpanda
Same circuit as the BA-71... These are the earlier version with 4 germanium transistors. I have two more that I am keeping for sure, but I would love for these two to go to a good home. You'll need to put your own pigtails on these; they do have built in power supplies, however, so the rack job is easy as pie. I'd love to get 600 for the pair but I would consider letting them go individually so make an offer.

Posted: Thu Nov 30, 2006 4:49 pm
by getreel
pics?

Posted: Thu Nov 30, 2006 6:40 pm
by sandpanda
They are in great condition, I can take pics tomorrow to post.

Posted: Fri Dec 01, 2006 11:39 am
by sandpanda
Unfortunately my actual camera isn't working, but I just took these with my phone:

Image
Image

Posted: Fri Dec 01, 2006 2:35 pm
by drumsound
So besides the pigtails are these thing ready to use? How do they get power?

Posted: Fri Dec 01, 2006 2:52 pm
by sandpanda
Yes totally ready to use... they have built-in power supplies, meaning you just hook them up to 110VAC and you're good to go.

Posted: Fri Dec 01, 2006 3:31 pm
by drumsound
Ya interested in a Brick?

Posted: Sat Dec 02, 2006 5:29 pm
by syrupcore
what are pigtails?

Posted: Sat Dec 02, 2006 6:57 pm
by sandpanda
It's basically half an xlr cable so you can hook the mic right up to it.

Posted: Sat Dec 02, 2006 9:48 pm
by emrr
Sorry to spoil your description, but those are BA-31A's with the factory upgrade cicuit boards, which have only one germanium transistor. Which makes them BA-31B's or BA-31C's in BA-31A clothing. A real 'A' variant has six transistors, all of which are germanium. They are fucking rare as hell, because they were almost all upgraded in 1961 when RCA pushed the replacement boards on everyone who'd bought the 'inferior' six transistor version. Look up the transistor #'s if you are in doubt. The schematic online at waltzingbear.com is incorrectly labeled; it is actually the BA-31C.

Posted: Mon Dec 04, 2006 9:11 pm
by sandpanda
You are correct, sir. However, not knowing that the A's were far rarer and more desireable, I'm not asking more than I've seen B's going for. If anyone cares to make an offer, I'm certainly amenable to that.

Posted: Mon Dec 04, 2006 10:08 pm
by emrr
Sorry, neglected to say your price seems correct. And these are real cool sounding units.

Posted: Wed Dec 06, 2006 8:54 am
by spacelabstudio
How do you set gain?

Posted: Wed Dec 06, 2006 11:14 am
by ???????
was wondering that myself!!!

Posted: Wed Dec 06, 2006 11:24 am
by drumsound
Probably set gain like an old Tele V72. The 'trick' is to put a comp or a console fader after the pre to control the level to tape.